Glutathione S-transferases and esterases in placenta after normal and pre-eclamptic pregnancies

Severe pre-eclampsia reduced significantly (P<0.05) by 68 +/- 6 per cent (mean +/-SEM, n=10) the maximal velocity (V-max) and, consequently, reduced significantly by 60 +/- 7 per cent the catalytic efficiency (C-E) of placental glutathione transferase pi, assayed with ethacrynic acid. Mild and severe pre-eclampsia reduced significantly by 82 +/- 5 per cent (mean +/-SEM, n=5) and by 41 +/- 5 per cent (mean +/-SEM, n= 10), respectively, the V-max and, consequently, reduced significantly by 72 +/- 7 and by 33 +/- 13 per cent, respectively, the CE of esterase, assayed with p-nitrophenyl acetate. Furthermore, severe pre-eclampsia increased significantly by 296 +/- 78 per cent the Michaelis-Menten constant (K-m) of total GST, assayed with chlorodinitrobenzene and, consequently, decreased significantly the C-E by 83 +/- 3 per cent. On the other hand, the concentrations of total and non-protein thiols did not change significantly in placental homogenates from patients with mild or severe pre-eclampsia compared to normal pregnancies. These findings would indicate a decreased capacity of the glutathione transferases and esterase detoxification systems to protect the fetus from drugs prescribed to pregnant women suffering pre-eclampsia, mainly in the severe phase. (C) 2003 Elsevier Ltd. All rights reserved.